Search Everything

Tip: Search using "First Name + Last Name", e.g.
János Kiss instead of Kiss János.

Publications - 6374

Damping of Dry Sand in Resonant Column-Torsional Simple Shear Device

Majd Ahmad R. P. Ray

Publication Name: Sustainability Switzerland

Publication Date: 2023-07-01

Volume: 15

Issue: 14

Page Range: Unknown

Description:

The damping ratio values of three different Danube sands were measured in the Resonant Column-Torsional Simple Shear device (RC-TOSS). The distinctive configuration of the RC-TOSS device employed in this investigation enabled the performance of both tests using a single sample. This research estimates and compares the damping ratio values measured with three distinct methods (two of which are in the RC test): The Free Vibration Decay (FVD), the Steady-State Vibration (SSV) methods, and the method of calculating the damping ratio from the hysteretic loops generated in the TOSS test. Both dense and loose samples were tested up to a peak-to-peak amplitude shear strain of 1%. The device provides measurements over a wide range of shear strain amplitudes. The results support the employment of the SSV methods at low strains (below 0.005%), while the FVD method gives a better estimate at higher strains (above 0.03%). The two methods and the TOSS results are in agreement with each other between 0.005% and 0.03%. The effect of the number of cycles on the damping ratio was investigated where a significant decrease was observed in the damping ratio with an increasing number of cycles. A parameter is introduced to describe the rate of this decrease, which should be considered during the structural design to reduce maintenance and life-cycle costs and enhance sustainability.

Open Access: Yes

DOI: 10.3390/su151411060

Linear-Matrix-Inequality-Based Controller and Observer Design for Induction Machine

Miklós Kuczmann Zoltan Nemeth

Publication Name: Electronics Switzerland

Publication Date: 2022-12-01

Volume: 11

Issue: 23

Page Range: Unknown

Description:

The modeling and drive control of electric machines are still actively researched scientific topics. Most of the existing models contain parameters that have no physical content or cannot be measured at all. For this reason, the use of observers in modern drive control algorithms is necessary. The main goal of this paper is to present the mathematical formalism of a linear matrix inequality (LMI)-based controller-observer design for a tensor product (TP) transformation-based model, including its implementation in a simulation environment. Based solely upon simulation results, the designed observer can provide a stable and accurate state space variable, regardless of the highly nonlinear induction machine model.

Open Access: Yes

DOI: 10.3390/electronics11233894

Tribological Properties of Nano-Sized ZrO2 Ceramic Particles in Automotive Lubricants

Rajmund Kuti D. Tóth I. Szabó

Publication Name: Fme Transactions

Publication Date: 2021-01-01

Volume: 49

Issue: 1

Page Range: 36-43

Description:

The demand for decreasing CO2-emission and harmful material content of the exhaust gas of passenger cars requires the improvement of the entire powertrain including the applied lubricants. One of the possible future engines lubricant can be the nano-sized ceramic particles, which can provide positive tribological properties also in the presence of nonmetallic surface materials. This paper presents the experimental investigation of ZrO2 nanoceramic powder as a lubricant additive. The tribological performance of the lubricant samples was experimentally investigated on a ball-on-disc translation tribometer. An optimum concentration was found at 0.4 wt%, where the wear scar diameter on the ball specimen was reduced by more than 40% compared to the reference sample. The SEM-analysis confirmed the mending mechanism theory: nanoparticles were revealed to aggregate between the asperities resulting in a significantly smoother contact surface.

Open Access: Yes

DOI: 10.5937/FME2101036T

Performance analysis and comparison of different DNS64 implementations for Linux, OpenBSD and FreeBSD

Sándor Répás Gábor Lencse

Publication Name: Proceedings International Conference on Advanced Information Networking and Applications AINA

Publication Date: 2013-08-08

Volume: Unknown

Issue: Unknown

Page Range: 877-884

Description:

The transition mechanisms for the first phase of IPv6 deployment are surveyed and the most important DNS64 solutions are selected. The test environment and the testing method are described. As for the selected DNS64 implementations, the performance of both BIND9 and TOTD running under Linux, OpenBSD and FreeBSD are measured and compared. The stability of all the tested DNS64 solutions was analyzed under serious overload conditions to test if they may be used in production environments with strong response time requirements. © 2013 IEEE.

Open Access: Yes

DOI: 10.1109/AINA.2013.80

Resurgent Africa: A Socialist Past, a Multipolar Present: Introduction

Adam Mayer

Publication Name: International Critical Thought

Publication Date: 2025-01-01

Volume: 15

Issue: 2

Page Range: 153-166

Description:

Africa’s 20th century national liberation heroes and African Marxist thinkers have identified Africa’s predicament as one of neo-colonialism. Political experiments in Africa during the Cold War had built on the revolutionary experiences of China (in Mauritania, Ghana, Zambia, Tanzania, Zimbabwe, Uganda, Guinea, Guinea-Bissau, Mali, Sudan, Somalia, and Benin) and the USSR (in Ethiopia, Sudan, Ghana, the African National Congress in South Africa, Angola, Mozambique, Congo Brazzaville, and Madagascar). China’s opening up in the late 1970s, as well as the painful Soviet re-capitalisation in 1991, ushered in the world’s “unipolar moment.” The “Washington consensus” and its neoliberalism destroyed Africa’s potential, deindustrialized the continent, and, with INGO (international non-government organization) conditionality and donor dominated relationships, looted Africa’s primary resources and agricultural produce for Western corporate benefit while perpetuating ineffectual aid systems for the continent’s people. The 1990s brought genocidal wars and the near-disappearance of African statehood, while raw materials found their way to the Global North at giveaway prices. Twenty years of renewed African engagement with China altered this framework in a decisive way: the Belt and Road Initiative has helped rebuild Africa’s infrastructure; China has become Africa’s number one direct capital investor; FOCAC (Forum on China-Africa Cooperation) has strengthened win-win relationships; and China has played a role in building common security with Africa.

Open Access: Yes

DOI: 10.1080/21598282.2025.2511108

FEM-Based Power Transformer Model for Superconducting and Conventional Power Transformer Optimization

Tamas Orosz

Publication Name: Energies

Publication Date: 2022-09-01

Volume: 15

Issue: 17

Page Range: Unknown

Description:

There were many promising superconducting materials discovered in the last decades that can significantly increase the efficiency of large power transformers. However, these large machines are generally custom-made and tailored to the given application. During the design process the most economical design should be selected from thousands of applicable solutions in a short design period. Due to the nonlinearity of the task, the cost-optimal transformer design, which has the smallest costs during the transformers’ planned lifetime, is usually not the design with the highest efficiency. Due to the topic’s importance, many simplified transformer models were published in the literature to resolve this problem. However, only a few papers considered this preliminary design optimization problem in the case of superconducting transformers and none of them made a comparison with a validated conventional transformer optimization model. This paper proposes a novel FEM-based two-winding transformer model, which can be used to calculate the main dimension of conventional and superconducting transformer designs. The models are stored in a unified JSON-file format, which can be easily integrated into an evolutionary or genetic algorithm-based optimization. The paper shows the used methods and their accuracy on conventional 10 MVA and superconducting 1.2 MVA transformer designs. Moreover, a simple cost optimization with the 10 MVA transformer was performed for two realistic economic scenarios. The results show that in some cases the cheaper, but less efficient, transformer can be the more economic.

Open Access: Yes

DOI: 10.3390/en15176177

A rule-based expert system for automatic question classification in mathematics adaptive assessment on indonesian elementary school environment

Siti Rochimah Umi Laili Yuhana A. Tormási Eko Mulyanto Yuniarno Aliia Rysbekova Mauridhi Hery Purnomo Laszlo T. Koczy

Publication Name: International Journal of Innovative Computing Information and Control

Publication Date: 2019-02-01

Volume: 15

Issue: 1

Page Range: 143-161

Description:

This paper is part of research in developing a competency-based assessment system for mathematics in Indonesian elementary school environment. An essential task is to accurately classify questions based on competency and difficulty level. Thus, an expert system is needed to classify those questions since competency information is often manually defined by experts. The objectives of this work are replacing a human expert’s role in the related knowledge engineering process and providing a rule-based expert system to supersede an expert to classify the questions. Five types of the rule-based algorithm: OneR, RIPPER, PART, FURIA, and J48, were applied to the dataset, which is comprised of 9454 real mathematics examination questions collected from several Indonesian elementary schools. Following the knowledge engineering principles, these algorithms generated the classification rules based on a pattern of the data. The rules of the best performing algorithm were utilized by a knowledge base for inference. Finally, to be able to fully measure the system performance, ten expert teachers were involved in the question classification step. The results confirm that the system meets the stated objectives in classifying the competency and the difficulty level of a question automatically.

Open Access: Yes

DOI: 10.24507/ijicic.15.01.143

From cross-helix knowledge to societal impact: The role of network diversity, innovation capabilities, and policy dynamism

Irum Shahzadi Yuwen Ning Dariusz Cichon Canghong Wang Irum Shahzadi Pu yan Nie

Publication Name: Technological Forecasting and Social Change

Publication Date: 2026-05-01

Volume: 226

Issue: Unknown

Page Range: Unknown

Description:

Innovation ecosystems today are under more pressure than ever to not only improve technology but also solve social and environmental problems. This study, informed by the Triple Helix Theory and Public Value Theory, formulates and evaluates a multilevel framework elucidating how collaboration across universities, industry, and governments can produce sustainable and socially beneficial innovation outcomes. The model analyses the contributions of Cross-Helix Knowledge Co-Creation Intensity (CKCI) and Public Value Orientation of Innovation (PVOI) to the development of Network Structural Diversity (NSD), which subsequently enhances Sustainable Innovation Capabilities (SIC). The study utilizes data from pivotal innovation sectors in the US and UK, demonstrating that SIC is a strong predictor of both Societal Impact Performance (SIP) and Triple Helix Sustainability Synergy (THSS). A serial mediation pathway from CKCI and PVOI through NSD and SIC is established, demonstrating that collaborative knowledge and public value orientation collectively yield beneficial social outcomes. The moderating effect of Policy Environment Dynamism (PED) on the relationship between SIC and SIP was not significant, indicating that robust internal capacities can still influence social outcomes in unstable policy environments. This study offers theoretical and practical insights for businesses aiming to develop inclusive, mission-oriented, and resilient innovation ecosystems.

Open Access: Yes

DOI: 10.1016/j.techfore.2026.124580

Combining transmission geometry laser ablation and a noncontact continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging

Olga S. Ovchinnikova Vilmos Kertesz Gary J. Van Berkel

Publication Name: Rapid Communications in Mass Spectrometry

Publication Date: 2011-12-30

Volume: 25

Issue: 24

Page Range: 3735-3740

Description:

This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid-phase sample collection into a continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging. The flow probe/emitter device was placed in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collected was immediately aspirated into the probe and onto the electrospray emitter, ionized and detected with the mass spectrometer. Freehand drawn ink lines and letters and an inked fingerprint on microscope slides were analyzed. The circular laser ablation area was about 210 μm in diameter and under the conditions used in these experiments the spatial resolution, as determined by the size of the surface features distinguished in the chemical images, was about 100 μm. Copyright © 2011 John Wiley & Sons, Ltd.

Open Access: Yes

DOI: 10.1002/rcm.5285